Not completely irrelevant. They may be trying to win now, but they also want to win in the next few seasons too since they appear to have the required talent (and cash) to stick around for a few years.
My guess is that they would be happy to take Griffey's salary off our hands, but not throw in Hill too. He's their 2nd best pitcher. They aren't going to trade him for a 1 year risk.
I would bet the house that every single team in baseball would take Hamilton before Griffey. They both have their injury concerns, but Griffey's are worse. And it's arguable who the better hitter is right now. Factoring in defense, I'd take Hamilton straight up while ignoring age and salary.
The proposed Griffey for Hill is living in a dream world. Hamilton for Hill would be opn to debate, but with the pitching market way out of whack, Hill has more value, by quite a bit.